Add `.html` support (#3867)

* feat: add html package

* feat: support assets in HTML

* feat(html): upgrade html integration

* feat(html): add `@astrojs/html` integration

* feat(html): add html support to astro core

* test(html): update html tests with package.json files

* chore: add changeset

* fix: remove import cycle

* chore: fix types

* refactor: remove @astrojs/html, add to core

* chore: update types for `*.html`

* fix: move *.html to astro/env

Co-authored-by: Nate Moore <nate@astro.build>

32 files changed, 534 insertions, 12 deletions

diff --git a/.changeset/strong-stingrays-compete.md b/.changeset/strong-stingrays-compete.md
new file mode 100644
index 000000000..f01d4cc8c
--- /dev/null
+++ b/.changeset/strong-stingrays-compete.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Add support for `.html` components and pages
diff --git a/packages/astro/env.d.ts b/packages/astro/env.d.ts
index aa649c896..619a4422b 100644
--- a/packages/astro/env.d.ts
+++ b/packages/astro/env.d.ts
@@ -26,3 +26,8 @@ declare module '*.md' {
 	const load: MD['default'];
 	export default load;
 }
+
+declare module "*.html" {
+  const Component: { render(opts: { slots: Record<string, string> }): string };
+  export default Component;
+}
diff --git a/packages/astro/package.json b/packages/astro/package.json
index 8d5a27e49..3e1e13fec 100644
--- a/packages/astro/package.json
+++ b/packages/astro/package.json
@@ -125,6 +125,7 @@
     "prismjs": "^1.28.0",
     "prompts": "^2.4.2",
     "recast": "^0.20.5",
+    "rehype": "^12.0.1",
     "resolve": "^1.22.0",
     "rollup": "^2.75.6",
     "semver": "^7.3.7",
@@ -136,6 +137,8 @@
     "strip-ansi": "^7.0.1",
     "supports-esm": "^1.0.0",
     "tsconfig-resolver": "^3.0.1",
+    "unist-util-visit": "^4.1.0",
+    "vfile": "^5.3.2",
     "vite": "3.0.2",
     "yargs-parser": "^21.0.1",
     "zod": "^3.17.3"
diff --git a/packages/astro/src/core/config.ts b/packages/astro/src/core/config.ts
index 75fabdc89..bbfad0439 100644
--- a/packages/astro/src/core/config.ts
+++ b/packages/astro/src/core/config.ts
@@ -325,7 +325,7 @@ export async function validateConfig(
 	const result = {
 		...(await AstroConfigRelativeSchema.parseAsync(userConfig)),
 		_ctx: {
-			pageExtensions: ['.astro', '.md'],
+			pageExtensions: ['.astro', '.md', '.html'],
 			scripts: [],
 			renderers: [],
 			injectedRoutes: [],
diff --git a/packages/astro/src/core/create-vite.ts b/packages/astro/src/core/create-vite.ts
index c853b29c7..72e357470 100644
--- a/packages/astro/src/core/create-vite.ts
+++ b/packages/astro/src/core/create-vite.ts
@@ -11,6 +11,7 @@ import configAliasVitePlugin from '../vite-plugin-config-alias/index.js';
 import envVitePlugin from '../vite-plugin-env/index.js';
 import astroIntegrationsContainerPlugin from '../vite-plugin-integrations-container/index.js';
 import jsxVitePlugin from '../vite-plugin-jsx/index.js';
+import htmlVitePlugin from '../vite-plugin-html/index.js';
 import markdownVitePlugin from '../vite-plugin-markdown/index.js';
 import astroScriptsPlugin from '../vite-plugin-scripts/index.js';
 import { createCustomViteLogger } from './errors.js';
@@ -73,6 +74,7 @@ export async function createVite(
 			mode === 'dev' && astroViteServerPlugin({ config: astroConfig, logging }),
 			envVitePlugin({ config: astroConfig }),
 			markdownVitePlugin({ config: astroConfig }),
+			htmlVitePlugin(),
 			jsxVitePlugin({ config: astroConfig, logging }),
 			astroPostprocessVitePlugin({ config: astroConfig }),
 			astroIntegrationsContainerPlugin({ config: astroConfig }),
diff --git a/packages/astro/src/core/dev/index.ts b/packages/astro/src/core/dev/index.ts
index df26858e5..eff09c5a4 100644
--- a/packages/astro/src/core/dev/index.ts
+++ b/packages/astro/src/core/dev/index.ts
@@ -45,14 +45,7 @@ export default async function dev(config: AstroConfig, options: DevOptions): Pro
 			mode: 'development',
 			server: { host },
 			optimizeDeps: {
-				include: [
-					'astro/client/idle.js',
-					'astro/client/load.js',
-					'astro/client/visible.js',
-					'astro/client/media.js',
-					'astro/client/only.js',
-					...rendererClientEntries,
-				],
+				include: rendererClientEntries,
 			},
 		},
 		{ astroConfig: config, logging: options.logging, mode: 'dev' }
diff --git a/packages/astro/src/core/errors.ts b/packages/astro/src/core/errors.ts
index 49bf4b6f2..13eec5cb8 100644
--- a/packages/astro/src/core/errors.ts
+++ b/packages/astro/src/core/errors.ts
@@ -58,7 +58,8 @@ export function fixViteErrorMessage(_err: unknown, server: ViteDevServer, filePa
 			const content = fs.readFileSync(fileURLToPath(filePath)).toString();
 			const lns = content.split('\n');
 			const line = lns.findIndex((ln) => ln.includes(importName));
-			const column = lns[line].indexOf(importName);
+			if (line == -1) return err;
+			const column = lns[line]?.indexOf(importName);
 			if (!(err as any).id) {
 				(err as any).id = `${fileURLToPath(filePath)}:${line + 1}:${column + 1}`;
 			}
diff --git a/packages/astro/src/runtime/server/index.ts b/packages/astro/src/runtime/server/index.ts
index dc48c1ecb..9dbd4af41 100644
--- a/packages/astro/src/runtime/server/index.ts
+++ b/packages/astro/src/runtime/server/index.ts
@@ -210,6 +210,21 @@ export async function renderComponent(
 		return markHTMLString(children);
 	}
 
+	if (Component && typeof Component === 'object' && (Component as any)['astro:html']) {
+		const children: Record<string, string> = {};
+		if (slots) {
+			await Promise.all(
+				Object.entries(slots).map(([key, value]) =>
+					renderSlot(result, value as string).then((output) => {
+						children[key] = output;
+					})
+				)
+			);
+		}
+		const html = (Component as any).render({ slots: children });
+		return markHTMLString(html);
+	}
+
 	if (Component && (Component as any).isAstroComponentFactory) {
 		async function* renderAstroComponentInline(): AsyncGenerator<string, void, undefined> {
 			let iterable = await renderToIterable(result, Component as any, _props, slots);
@@ -265,6 +280,7 @@ Did you mean to add ${formatList(probableRendererNames.map((r) => '`' + r + '`')
 			)
 		);
 	}
+
 	// Call the renderers `check` hook to see if any claim this component.
 	let renderer: SSRLoadedRenderer | undefined;
 	if (metadata.hydrate !== 'only') {
diff --git a/packages/astro/src/vite-plugin-html/index.ts b/packages/astro/src/vite-plugin-html/index.ts
new file mode 100644
index 000000000..c593bc201
--- /dev/null
+++ b/packages/astro/src/vite-plugin-html/index.ts
@@ -0,0 +1,14 @@
+import { transform } from './transform/index.js';
+
+export default function html() {
+	return {
+		name: 'astro:html',
+		options(options: any) {
+			options.plugins = options.plugins?.filter((p: any) => p.name !== 'vite:build-html');
+		},
+		async transform(source: string, id: string) {
+			if (!id.endsWith('.html')) return;
+			return await transform(source, id);
+		}
+	}
+}
diff --git a/packages/astro/src/vite-plugin-html/transform/escape.ts b/packages/astro/src/vite-plugin-html/transform/escape.ts
new file mode 100644
index 000000000..8b5805614
--- /dev/null
+++ b/packages/astro/src/vite-plugin-html/transform/escape.ts
@@ -0,0 +1,27 @@
+import type { Plugin } from 'unified';
+import type { Root, RootContent } from 'hast';
+import type MagicString from 'magic-string';
+import { visit } from 'unist-util-visit';
+
+import { replaceAttribute, needsEscape, escape } from './utils.js';
+
+const rehypeEscape: Plugin<[{ s: MagicString }], Root> = ({ s }) => {
+	return (tree, file) => {
+		visit(tree, (node: Root | RootContent, index, parent) => {
+			if (node.type === 'text' || node.type === 'comment') {
+				if (needsEscape(node.value)) {
+					s.overwrite(node.position!.start.offset!, node.position!.end.offset!, escape(node.value));
+				}
+			} else if (node.type === 'element') {
+				for (const [key, value] of Object.entries(node.properties ?? {})) {
+					const newKey = needsEscape(key) ? escape(key) : key;
+					const newValue = needsEscape(value) ? escape(value) : value;
+					if (newKey === key && newValue === value) continue;
+					replaceAttribute(s, node, key, (value === '') ? newKey : `${newKey}="${newValue}"`);
+				}
+			}
+		});
+	};
+};
+
+export default rehypeEscape;
diff --git a/packages/astro/src/vite-plugin-html/transform/index.ts b/packages/astro/src/vite-plugin-html/transform/index.ts
new file mode 100644
index 000000000..de6431ea7
--- /dev/null
+++ b/packages/astro/src/vite-plugin-html/transform/index.ts
@@ -0,0 +1,32 @@
+import MagicString from 'magic-string';
+import { rehype } from 'rehype';
+import { VFile } from 'vfile';
+import escape from './escape.js';
+import slots, { SLOT_PREFIX } from './slots.js';
+
+export async function transform(code: string, id: string) {
+	const s = new MagicString(code, { filename: id });
+	const imports = new Map();
+	const parser = rehype()
+		.data('settings', { fragment: true })
+		.use(escape, { s })
+		.use(slots, { s });
+
+	const vfile = new VFile({ value: code, path: id })
+	await parser.process(vfile)
+	s.prepend(`export default {\n\t"astro:html": true,\n\trender({ slots: ${SLOT_PREFIX} }) {\n\t\treturn \``);
+	s.append('`\n\t}\n}');
+
+	if (imports.size > 0) {
+		let importText = ''
+		for (const [path, importName] of imports.entries()) {
+			importText += `import ${importName} from "${path}";\n`
+		}
+		s.prepend(importText);
+	}
+
+	return {
+		code: s.toString(),
+		map: s.generateMap()
+	}
+}
diff --git a/packages/astro/src/vite-plugin-html/transform/slots.ts b/packages/astro/src/vite-plugin-html/transform/slots.ts
new file mode 100644
index 000000000..c8cb32f13
--- /dev/null
+++ b/packages/astro/src/vite-plugin-html/transform/slots.ts
@@ -0,0 +1,27 @@
+import type { Plugin } from 'unified';
+import type { Root, RootContent } from 'hast';
+
+import { visit } from 'unist-util-visit';
+import MagicString from 'magic-string';
+import { escape } from './utils.js';
+
+const rehypeSlots: Plugin<[{ s: MagicString }], Root> = ({ s }) => {
+  return (tree, file) => {
+    visit(tree, (node: Root | RootContent, index, parent) => {
+      if (node.type === 'element' && node.tagName === 'slot') {
+				if (typeof node.properties?.['is:inline'] !== 'undefined') return;
+				const name = node.properties?.['name'] ?? 'default';
+				const start = node.position?.start.offset ?? 0;
+				const end = node.position?.end.offset ?? 0;
+				const first = node.children.at(0) ?? node;
+				const last = node.children.at(-1) ?? node;
+				const text = file.value.slice(first.position?.start.offset ?? 0, last.position?.end.offset ?? 0).toString();
+				s.overwrite(start, end, `\${${SLOT_PREFIX}["${name}"] ?? \`${escape(text).trim()}\`}`)
+      }
+    });
+  }
+}
+
+export default rehypeSlots;
+
+export const SLOT_PREFIX = `___SLOTS___`;
diff --git a/packages/astro/src/vite-plugin-html/transform/utils.ts b/packages/astro/src/vite-plugin-html/transform/utils.ts
new file mode 100644
index 000000000..313bfe662
--- /dev/null
+++ b/packages/astro/src/vite-plugin-html/transform/utils.ts
@@ -0,0 +1,27 @@
+import type { Element } from 'hast';
+import MagicString from 'magic-string';
+
+const splitAttrsTokenizer = /([\$\{\}\@a-z0-9_\:\-]*)\s*?=\s*?(['"]?)(.*?)\2\s+/gim;
+
+export function replaceAttribute(s: MagicString, node: Element, key: string, newValue: string) {
+	splitAttrsTokenizer.lastIndex = 0;
+	const text = s.original.slice(node.position?.start.offset ?? 0, node.position?.end.offset ?? 0).toString();
+	const offset = text.indexOf(key);
+	if (offset === -1) return;
+	const start = node.position!.start.offset! + offset;
+	const tokens = text.slice(offset).split(splitAttrsTokenizer);
+	const token = tokens[0].replace(/([^>])(\>[\s\S]*$)/gmi, '$1');
+	if (token.trim() === key) {
+		const end = start + key.length;
+		s.overwrite(start, end, newValue)
+	} else {
+		const end = start + `${key}=${tokens[2]}${tokens[3]}${tokens[2]}`.length;
+		s.overwrite(start, end, newValue)
+	}
+}
+export function needsEscape(value: any): value is string {
+	return typeof value === 'string' && (value.includes('`') || value.includes('${'));
+}
+export function escape(value: string) {
+	return value.replace(/`/g, '\\`').replace(/\$\{/g, '\\${');
+}
diff --git a/packages/astro/test/fixtures/html-component/package.json b/packages/astro/test/fixtures/html-component/package.json
new file mode 100644
index 000000000..548f0bc7b
--- /dev/null
+++ b/packages/astro/test/fixtures/html-component/package.json
@@ -0,0 +1,8 @@
+{
+  "name": "@test/html-component",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "astro": "workspace:*"
+  }
+}
diff --git a/packages/astro/test/fixtures/html-component/src/components/Test.html b/packages/astro/test/fixtures/html-component/src/components/Test.html
new file mode 100644
index 000000000..ec16bf314
--- /dev/null
+++ b/packages/astro/test/fixtures/html-component/src/components/Test.html
@@ -0,0 +1,3 @@
+<h1>Hello component!</h1>
+
+<div id="foo">bar</div>
diff --git a/packages/astro/test/fixtures/html-component/src/pages/index.astro b/packages/astro/test/fixtures/html-component/src/pages/index.astro
new file mode 100644
index 000000000..821d12538
--- /dev/null
+++ b/packages/astro/test/fixtures/html-component/src/pages/index.astro
@@ -0,0 +1,5 @@
+---
+import Test from '../components/Test.html';
+---
+
+<Test />
diff --git a/packages/astro/test/fixtures/html-escape/package.json b/packages/astro/test/fixtures/html-escape/package.json
new file mode 100644
index 000000000..b6eb74765
--- /dev/null
+++ b/packages/astro/test/fixtures/html-escape/package.json
@@ -0,0 +1,8 @@
+{
+  "name": "@test/html-escape",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "astro": "workspace:*"
+  }
+}
diff --git a/packages/astro/test/fixtures/html-escape/src/components/Test.html b/packages/astro/test/fixtures/html-escape/src/components/Test.html
new file mode 100644
index 000000000..6ee4b5200
--- /dev/null
+++ b/packages/astro/test/fixtures/html-escape/src/components/Test.html
@@ -0,0 +1,4 @@
+<div>${foo}</div>
+<span ${attr}></span>
+<custom-element x-data="`${test}`"></custom-element>
+<script>console.log(`hello ${"world"}!`)</script>
diff --git a/packages/astro/test/fixtures/html-escape/src/pages/index.astro b/packages/astro/test/fixtures/html-escape/src/pages/index.astro
new file mode 100644
index 000000000..821d12538
--- /dev/null
+++ b/packages/astro/test/fixtures/html-escape/src/pages/index.astro
@@ -0,0 +1,5 @@
+---
+import Test from '../components/Test.html';
+---
+
+<Test />
diff --git a/packages/astro/test/fixtures/html-page/package.json b/packages/astro/test/fixtures/html-page/package.json
new file mode 100644
index 000000000..070024b1e
--- /dev/null
+++ b/packages/astro/test/fixtures/html-page/package.json
@@ -0,0 +1,8 @@
+{
+  "name": "@test/html-page",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "astro": "workspace:*"
+  }
+}
diff --git a/packages/astro/test/fixtures/html-page/src/pages/index.html b/packages/astro/test/fixtures/html-page/src/pages/index.html
new file mode 100644
index 000000000..5d4d22827
--- /dev/null
+++ b/packages/astro/test/fixtures/html-page/src/pages/index.html
@@ -0,0 +1 @@
+<h1>Hello page!</h1>
diff --git a/packages/astro/test/fixtures/html-slots/package.json b/packages/astro/test/fixtures/html-slots/package.json
new file mode 100644
index 000000000..10b04cfd4
--- /dev/null
+++ b/packages/astro/test/fixtures/html-slots/package.json
@@ -0,0 +1,8 @@
+{
+  "name": "@test/html-slots",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "astro": "workspace:*"
+  }
+}
diff --git a/packages/astro/test/fixtures/html-slots/src/components/Default.html b/packages/astro/test/fixtures/html-slots/src/components/Default.html
new file mode 100644
index 000000000..9f012095f
--- /dev/null
+++ b/packages/astro/test/fixtures/html-slots/src/components/Default.html
@@ -0,0 +1 @@
+<div id="default"><slot></slot></div>
diff --git a/packages/astro/test/fixtures/html-slots/src/components/Inline.html b/packages/astro/test/fixtures/html-slots/src/components/Inline.html
new file mode 100644
index 000000000..121164e38
--- /dev/null
+++ b/packages/astro/test/fixtures/html-slots/src/components/Inline.html
@@ -0,0 +1 @@
+<div id="inline"><slot is:inline></slot></div>
diff --git a/packages/astro/test/fixtures/html-slots/src/components/Named.html b/packages/astro/test/fixtures/html-slots/src/components/Named.html
new file mode 100644
index 000000000..0993cfb27
--- /dev/null
+++ b/packages/astro/test/fixtures/html-slots/src/components/Named.html
@@ -0,0 +1,3 @@
+<div id="a"><slot name="a"></slot></div>
+<div id="b"><slot name="b"></slot></div>
+<div id="c"><slot name="c"></slot></div>
diff --git a/packages/astro/test/fixtures/html-slots/src/pages/index.astro b/packages/astro/test/fixtures/html-slots/src/pages/index.astro
new file mode 100644
index 000000000..aa4a3bd25
--- /dev/null
+++ b/packages/astro/test/fixtures/html-slots/src/pages/index.astro
@@ -0,0 +1,13 @@
+---
+import Default from '../components/Default.html';
+import Named from '../components/Named.html';
+import Inline from '../components/Inline.html';
+---
+
+<Default>Default</Default>
+<Named>
+	<span slot="a">A</span>
+	<span slot="b">B</span>
+	<span slot="c">C</span>
+</Named>
+<Inline></Inline>
diff --git a/packages/astro/test/html-component.test.js b/packages/astro/test/html-component.test.js
new file mode 100644
index 000000000..0145a22aa
--- /dev/null
+++ b/packages/astro/test/html-component.test.js
@@ -0,0 +1,57 @@
+import { expect } from 'chai';
+import * as cheerio from 'cheerio';
+import { loadFixture } from './test-utils.js';
+
+describe('HTML Component', () => {
+	let fixture;
+
+	before(async () => {
+		fixture = await loadFixture({
+			root: './fixtures/html-component/',
+		});
+	});
+
+	describe('build', () => {
+		before(async () => {
+			await fixture.build();
+		});
+
+		it('works', async () => {
+			const html = await fixture.readFile('/index.html');
+			const $ = cheerio.load(html);
+
+			const h1 = $('h1');
+			const foo = $('#foo');
+
+			expect(h1.text()).to.equal('Hello component!');
+			expect(foo.text()).to.equal('bar');
+		});
+	});
+
+	describe('dev', () => {
+		let devServer;
+
+		before(async () => {
+			devServer = await fixture.startDevServer();
+		});
+
+		after(async () => {
+			await devServer.stop();
+		});
+
+		it('works', async () => {
+			const res = await fixture.fetch('/');
+
+			expect(res.status).to.equal(200);
+
+			const html = await res.text();
+			const $ = cheerio.load(html);
+
+			const h1 = $('h1');
+			const foo = $('#foo');
+
+			expect(h1.text()).to.equal('Hello component!');
+			expect(foo.text()).to.equal('bar');
+		});
+	});
+});
diff --git a/packages/astro/test/html-escape.test.js b/packages/astro/test/html-escape.test.js
new file mode 100644
index 000000000..ed19105c6
--- /dev/null
+++ b/packages/astro/test/html-escape.test.js
@@ -0,0 +1,69 @@
+import { expect } from 'chai';
+import * as cheerio from 'cheerio';
+import { loadFixture } from './test-utils.js';
+
+describe('HTML Escape', () => {
+	let fixture;
+
+	before(async () => {
+		fixture = await loadFixture({
+			root: './fixtures/html-escape/',
+		});
+	});
+
+	describe('build', () => {
+		before(async () => {
+			await fixture.build();
+		});
+
+		it('works', async () => {
+			const html = await fixture.readFile('/index.html');
+			const $ = cheerio.load(html);
+
+			const div = $('div');
+			expect(div.text()).to.equal('${foo}');
+
+			const span = $('span');
+			expect(span.attr('${attr}')).to.equal("");
+
+			const ce = $('custom-element');
+			expect(ce.attr('x-data')).to.equal("`${test}`");
+
+			const script = $('script');
+			expect(script.text()).to.equal('console.log(`hello ${"world"}!`)');
+		});
+	});
+
+	describe('dev', () => {
+		let devServer;
+
+		before(async () => {
+			devServer = await fixture.startDevServer();
+		});
+
+		after(async () => {
+			await devServer.stop();
+		});
+
+		it('works', async () => {
+			const res = await fixture.fetch('/');
+
+			expect(res.status).to.equal(200);
+
+			const html = await res.text();
+			const $ = cheerio.load(html);
+
+			const div = $('div');
+			expect(div.text()).to.equal('${foo}');
+
+			const span = $('span');
+			expect(span.attr('${attr}')).to.equal("");
+
+			const ce = $('custom-element');
+			expect(ce.attr('x-data')).to.equal("`${test}`");
+
+			const script = $('script');
+			expect(script.text()).to.equal('console.log(`hello ${"world"}!`)');
+		});
+	});
+});
diff --git a/packages/astro/test/html-page.test.js b/packages/astro/test/html-page.test.js
new file mode 100644
index 000000000..fe4c01f68
--- /dev/null
+++ b/packages/astro/test/html-page.test.js
@@ -0,0 +1,53 @@
+import { expect } from 'chai';
+import * as cheerio from 'cheerio';
+import { loadFixture } from './test-utils.js';
+
+describe('HTML Page', () => {
+	let fixture;
+
+	before(async () => {
+		fixture = await loadFixture({
+			root: './fixtures/html-page/',
+		});
+	});
+
+	describe('build', () => {
+		before(async () => {
+			await fixture.build();
+		});
+
+		it('works', async () => {
+			const html = await fixture.readFile('/index.html');
+			const $ = cheerio.load(html)
+
+			const h1 = $('h1');
+
+			expect(h1.text()).to.equal('Hello page!');
+		});
+	});
+
+	describe('dev', () => {
+		let devServer;
+
+		before(async () => {
+			devServer = await fixture.startDevServer();
+		});
+
+		after(async () => {
+			await devServer.stop();
+		});
+
+		it('works', async () => {
+			const res = await fixture.fetch('/');
+
+			expect(res.status).to.equal(200);
+
+			const html = await res.text();
+			const $ = cheerio.load(html)
+
+			const h1 = $('h1');
+
+			expect(h1.text()).to.equal('Hello page!');
+		});
+	});
+});
diff --git a/packages/astro/test/html-slots.test.js b/packages/astro/test/html-slots.test.js
new file mode 100644
index 000000000..af1a05a83
--- /dev/null
+++ b/packages/astro/test/html-slots.test.js
@@ -0,0 +1,75 @@
+import { expect } from 'chai';
+import * as cheerio from 'cheerio';
+import { loadFixture } from './test-utils.js';
+
+describe('HTML Slots', () => {
+	let fixture;
+
+	before(async () => {
+		fixture = await loadFixture({
+			root: './fixtures/html-slots/',
+		});
+	});
+
+	describe('build', () => {
+		before(async () => {
+			await fixture.build();
+		});
+
+		it('works', async () => {
+			const html = await fixture.readFile('/index.html');
+			const $ = cheerio.load(html);
+
+			const slotDefault = $('#default');
+			expect(slotDefault.text()).to.equal('Default');
+
+			const a = $('#a');
+			expect(a.text().trim()).to.equal('A');
+
+			const b = $('#b');
+			expect(b.text().trim()).to.equal('B');
+
+			const c = $('#c');
+			expect(c.text().trim()).to.equal('C');
+
+			const inline = $('#inline');
+			expect(inline.html()).to.equal('<slot is:inline=""></slot>');
+		});
+	});
+
+	describe('dev', () => {
+		let devServer;
+
+		before(async () => {
+			devServer = await fixture.startDevServer();
+		});
+
+		after(async () => {
+			await devServer.stop();
+		});
+
+		it('works', async () => {
+			const res = await fixture.fetch('/');
+
+			expect(res.status).to.equal(200);
+
+			const html = await res.text();
+			const $ = cheerio.load(html);
+
+			const slotDefault = $('#default');
+			expect(slotDefault.text()).to.equal('Default');
+
+			const a = $('#a');
+			expect(a.text().trim()).to.equal('A');
+
+			const b = $('#b');
+			expect(b.text().trim()).to.equal('B');
+
+			const c = $('#c');
+			expect(c.text().trim()).to.equal('C');
+
+			const inline = $('#inline');
+			expect(inline.html()).to.equal('<slot is:inline=""></slot>');
+		});
+	});
+});
diff --git a/packages/webapi/mod.d.ts b/packages/webapi/mod.d.ts
index a3c49dc5c..7150edbe7 100644
--- a/packages/webapi/mod.d.ts
+++ b/packages/webapi/mod.d.ts
@@ -9,4 +9,4 @@ interface PolyfillOptions {
     override?: Record<string, {
         (...args: any[]): any;
     }>;
-}
\ No newline at end of file
+}
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index e7816eb5b..bd34408fe 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -506,6 +506,7 @@ importers:
       prismjs: ^1.28.0
       prompts: ^2.4.2
       recast: ^0.20.5
+      rehype: ^12.0.1
       resolve: ^1.22.0
       rollup: ^2.75.6
       sass: ^1.52.2
@@ -519,6 +520,8 @@ importers:
       strip-ansi: ^7.0.1
       supports-esm: ^1.0.0
       tsconfig-resolver: ^3.0.1
+      unist-util-visit: ^4.1.0
+      vfile: ^5.3.2
       vite: 3.0.2
       yargs-parser: ^21.0.1
       zod: ^3.17.3
@@ -566,6 +569,7 @@ importers:
       prismjs: 1.28.0
       prompts: 2.4.2
       recast: 0.20.5
+      rehype: 12.0.1
       resolve: 1.22.1
       rollup: 2.76.0
       semver: 7.3.7
@@ -577,6 +581,8 @@ importers:
       strip-ansi: 7.0.1
       supports-esm: 1.0.0
       tsconfig-resolver: 3.0.1
+      unist-util-visit: 4.1.0
+      vfile: 5.3.4
       vite: 3.0.2_sass@1.53.0
       yargs-parser: 21.0.1
       zod: 3.17.3
@@ -1526,6 +1532,30 @@ importers:
     dependencies:
       astro: link:../../..
 
+  packages/astro/test/fixtures/html-component:
+    specifiers:
+      astro: workspace:*
+    dependencies:
+      astro: link:../../..
+
+  packages/astro/test/fixtures/html-escape:
+    specifiers:
+      astro: workspace:*
+    dependencies:
+      astro: link:../../..
+
+  packages/astro/test/fixtures/html-page:
+    specifiers:
+      astro: workspace:*
+    dependencies:
+      astro: link:../../..
+
+  packages/astro/test/fixtures/html-slots:
+    specifiers:
+      astro: workspace:*
+    dependencies:
+      astro: link:../../..
+
   packages/astro/test/fixtures/import-ts-with-js:
     specifiers:
       astro: workspace:*
@@ -9547,7 +9577,7 @@ packages:
     dev: true
 
   /concat-map/0.0.1:
-    resolution: {integrity: sha512-/Srv4dswyQNBfohGpz9o6Yb3Gz3SrUDqBH5rTuhGR7ahtlbYKnVxw2bCFMRljaA7EXHaXZ8wsHdodFvbkhKmqg==}
+    resolution: {integrity: sha1-2Klr13/Wjfd5OnMDajug1UBdR3s=}
 
   /concurrently/7.2.2:
     resolution: {integrity: sha512-DcQkI0ruil5BA/g7Xy3EWySGrFJovF5RYAYxwGvv9Jf9q9B1v3jPFP2tl6axExNf1qgF30kjoNYrangZ0ey4Aw==}
@@ -14217,6 +14247,15 @@ packages:
       unist-util-visit: 4.1.0
     dev: true
 
+  /rehype-parse/8.0.4:
+    resolution: {integrity: sha512-MJJKONunHjoTh4kc3dsM1v3C9kGrrxvA3U8PxZlP2SjH8RNUSrb+lF7Y0KVaUDnGH2QZ5vAn7ulkiajM9ifuqg==}
+    dependencies:
+      '@types/hast': 2.3.4
+      hast-util-from-parse5: 7.1.0
+      parse5: 6.0.1
+      unified: 10.1.2
+    dev: false
+
   /rehype-raw/6.1.1:
     resolution: {integrity: sha512-d6AKtisSRtDRX4aSPsJGTfnzrX2ZkHQLE5kiUuGOeEoLpbEulFF4hj0mLPbsa+7vmguDKOVVEQdHKDSwoaIDsQ==}
     dependencies:
@@ -14251,6 +14290,15 @@ packages:
       '@jsdevtools/rehype-toc': 3.0.2
     dev: true
 
+  /rehype/12.0.1:
+    resolution: {integrity: sha512-ey6kAqwLM3X6QnMDILJthGvG1m1ULROS9NT4uG9IDCuv08SFyLlreSuvOa//DgEvbXx62DS6elGVqusWhRUbgw==}
+    dependencies:
+      '@types/hast': 2.3.4
+      rehype-parse: 8.0.4
+      rehype-stringify: 9.0.3
+      unified: 10.1.2
+    dev: false
+
   /remark-code-titles/0.1.2:
     resolution: {integrity: sha512-KsHQbaI4FX8Ozxqk7YErxwmBiveUqloKuVqyPG2YPLHojpgomodWgRfG4B+bOtmn/5bfJ8khw4rR0lvgVFl2Uw==}
     dependencies: